Compounds of the formula ##STR2## wherein R is nitro or trifluoromethyl in 2 or 3-position are known to possess cerebral vasodilating effect, effect against angina pectoris or blood pressure lowering effect.
Agents which relax vascular smooth muscle may be used for treatment of arterial hypertension since such patients suffer from elevated peripheral resistance to blood flow. Compounds which interfere with vascular smooth muscle activity have been used clinically for several years. However, their usefulness has often been limited due to insufficient efficacy and/or due to adverse effects. Side effects (outside the cardiovascular system) have often been connected with properties of the agent not relevant to the smooth muscle relaxant effect. Sometimes the vasodilating agents have also exerted a negative effect on the contractility of the heart.
It appears that the development of specific smooth muscle relaxants devoid of adverse effects, can offer a therapeutic advantage in arterial hypertension and for treatment of ischaemic heart disease and of the acutely failing heart. Further more, such agents can also be useful in treatment of other conditions with excessive activation of smooth muscle of the visceral type.